At 88, 9-14 of the Journal of the Society of Dyers and Colourists (Jan. 1972), an aqueous dyeing system is described in which exceptionally short liquor ratios are employed by formulating the dyestuff with a foaming agent and converting the liquor to a foam on and in the substrate before raising temperature to fix the color.
Considerable interest has since developed in applying short liquor ratio techniques of this sort to piece goods wet processing, because of substantial operating economics that are potentially available, but progress in this field has been hampered by difficulties encountered in handling adequate piece good loads without inducing crush marks and other objectionable adverse influences in the piece goods as it is handled for wet processing at low liquor ratios. Such difficulties are eliminated according to the present invention by expanding the effective handling influence of the processing liquor at low liquor ratios by applying a foaming formulation of the processing liquor in a non-persistently foamed condition so that a portion of the processing liquor continually decays to liquid phase during the piece goods handling and can be recovered and continually recycle for reapplication during the wet processing treatment.